Hi Jacopo,
On Mon, Dec 14, 2020 at 11:37:50AM +0100, Jacopo Mondi wrote:
> On Sat, Dec 05, 2020 at 12:01:35AM +0200, Laurent Pinchart wrote:
> > devm_kzalloc() is the wrong API to allocate encoders, as the lifetime of
> > the encoders is tied to the DRM device, not the device to driver
> > binding. drmm_kzalloc() isn't a good option either, as it would result
> > in the encoder being freed before being unregistered during the managed
> > cleanup of the DRM objects. Use a plain kzalloc(), and register a drmm
> > action to cleanup the encoder.
> >
> > Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
> > ---
> > drivers/gpu/drm/rcar-du/rcar_du_encoder.c | 47 ++++++++++++++---------
> > 1 file changed, 29 insertions(+), 18 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/rcar-du/rcar_du_encoder.c b/drivers/gpu/drm/rcar-du/rcar_du_encoder.c
> > index 0edce24f2053..7c491ff72cd2 100644
> > --- a/drivers/gpu/drm/rcar-du/rcar_du_encoder.c
> > +++ b/drivers/gpu/drm/rcar-du/rcar_du_encoder.c
> > @@ -8,12 +8,13 @@
> > */
> >
> > #include <linux/export.h>
> > +#include <linux/slab.h>
> >
> > #include <drm/drm_bridge.h>
> > #include <drm/drm_crtc.h>
> > +#include <drm/drm_managed.h>
> > #include <drm/drm_modeset_helper_vtables.h>
> > #include <drm/drm_panel.h>
> > -#include <drm/drm_simple_kms_helper.h>
> >
> > #include "rcar_du_drv.h"
> > #include "rcar_du_encoder.h"
> > @@ -44,6 +45,17 @@ static unsigned int rcar_du_encoder_count_ports(struct device_node *node)
> > return num_ports;
> > }
> >
> > +static const struct drm_encoder_funcs rcar_du_encoder_funcs = {
> > +};
> > +
> > +static void rcar_du_encoder_release(struct drm_device *dev, void *res)
> > +{
> > + struct rcar_du_encoder *renc = res;
> > +
> > + drm_encoder_cleanup(&renc->base);
> > + kfree(renc);
> > +}
> > +
> > int rcar_du_encoder_init(struct rcar_du_device *rcdu,
> > enum rcar_du_output output,
> > struct device_node *enc_node)
> > @@ -53,7 +65,7 @@ int rcar_du_encoder_init(struct rcar_du_device *rcdu,
> > struct drm_bridge *bridge;
> > int ret;
> >
> > - renc = devm_kzalloc(rcdu->dev, sizeof(*renc), GFP_KERNEL);
> > + renc = kzalloc(sizeof(*renc), GFP_KERNEL);
> > if (renc == NULL)
> > return -ENOMEM;
> >
> > @@ -76,20 +88,20 @@ int rcar_du_encoder_init(struct rcar_du_device *rcdu,
> >
> > if (IS_ERR(panel)) {
> > ret = PTR_ERR(panel);
> > - goto done;
> > + goto error;
> > }
> >
> > bridge = devm_drm_panel_bridge_add_typed(rcdu->dev, panel,
> > DRM_MODE_CONNECTOR_DPI);
> > if (IS_ERR(bridge)) {
> > ret = PTR_ERR(bridge);
> > - goto done;
> > + goto error;
> > }
> > } else {
> > bridge = of_drm_find_bridge(enc_node);
> > if (!bridge) {
> > ret = -EPROBE_DEFER;
> > - goto done;
> > + goto error;
> > }
> >
> > if (output == RCAR_DU_OUTPUT_LVDS0 ||
> > @@ -104,28 +116,27 @@ int rcar_du_encoder_init(struct rcar_du_device *rcdu,
> > if (rcdu->info->gen >= 3 && output == RCAR_DU_OUTPUT_LVDS1) {
> > if (rcar_lvds_dual_link(bridge)) {
> > ret = -ENOLINK;
> > - goto done;
> > + goto error;
> > }
> > }
> >
> > - ret = drm_simple_encoder_init(rcdu->ddev, encoder,
> > - DRM_MODE_ENCODER_NONE);
> > + ret = drm_encoder_init(rcdu->ddev, encoder, &rcar_du_encoder_funcs,
> > + DRM_MODE_ENCODER_NONE, NULL);
>
> I might have missed the reason for this.
> Why add an action later instead of making rcar_du_encoder_release part
> of rcar_du_encoder_funcs ?
Because the subsystem is moving towards drmm_* instead of manual release
callbacks (I don't mind the manual release callbacks personally). Note
that there's "[PATCH v4 02/19] drm: add drmm_encoder_alloc()" that
should be merged soon, which will allow simplifying this.
> > if (ret < 0)
> > - goto done;
> > + goto error;
> > +
> > + ret = drmm_add_action_or_reset(rcdu->ddev, rcar_du_encoder_release,
> > + renc);
> > + if (ret)
> > + return ret;
> >
> > /*
> > * Attach the bridge to the encoder. The bridge will create the
> > * connector.
> > */
> > - ret = drm_bridge_attach(encoder, bridge, NULL, 0);
> > - if (ret) {
> > - drm_encoder_cleanup(encoder);
> > - return ret;
> > - }
> > -
> > -done:
> > - if (ret < 0)
> > - devm_kfree(rcdu->dev, renc);
> > + return drm_bridge_attach(encoder, bridge, NULL, 0);
> >
> > +error:
> > + kfree(renc);
> > return ret;
> > }
--
Regards,
Laurent Pinchart
